Our long-range objectives are to determine how the protein components, both soluble and membrane bound, of adrenal chromaffin vesicles are assembled into the intact vesicle. We also wish to determine whether de novo synthesis of membrane components occur or whether membranes from vesicles which had secreted their contents are utilized for new vesicle formation. Using perfused bovine adrenal glands we will follow the incorporation of 3H-leucine into 3H-chromogranin and both soluble and membrane bound 3H-dopamine-B-hydroxylose (DBH). 3H-chromogranin and soluble DBH serve as markers for the synthesis of soluble protein components of chromaffin vesicles while membrane-bound DBH serves as a marker for membrane protein synthesis. Our earlier studies have shown that nascent chromaffin vesicles have a lower bouyant density than do mature vesicles. By studying the time course of incorporation of these proteins into nascent vesicles we can obtain important information on how these vesicles are assembled. In subsequent studies we will also study the incorporation of lipid components into nascent vesicles. For these latter studies adrenal glands will be perfused with either 3H-acetate or 3H-choline and the formation of specific lipids in nacent vesicles. For these latter studies adrenal glands will be perfused with either 3H-acetate or 3H-choline and the formation of specific lipids in nascent vesicles determined.